Many different types of building or utility materials, such as wallboard insulation, blown-in insulation, acoustical or sound dampening/absorbing materials, etc., exist in the art. These are all designed to provide a specific function within a structure. In addition, the composition of ingredients or components making up these utility materials varies greatly. Although there are many different available compositions making up the many different utility materials, relatively few of these incorporate microparticles, such as naturally occurring cenospheres or Extendospheres™, or synthetically manufactured microparticles, into their makeup.
In addition, many different types of naturally occurring and artificial microparticles exist. Cenospheres are naturally occurring microparticles found in “fly ash,” which is formed during coal combustion. Cenospheres make up a small percentage (1%-4%) of fly ash. They are hollow particles with wall thicknesses about 10% of their diameter. Fly ash also includes small spherical solid particles that have a much higher bulk density than cenospheres.
In addition, there are several artificially manufactured microparticles used for a variety of purposes. Although such microparticles tend to be more consistent and uniform in their makeup and structure, they also tend to be extremely expensive and cost prohibitive for many applications.
Wallboard is a common utility or building material, which comes in many different types, designs, and sizes. Wallboard can be configured to exhibit many different properties or characteristics, such as different sound absorption, heat transfer and/or fire resistance properties. By far, the most common type of wallboard is drywall or gypsum board. Drywall comprises an inner core of gypsum, the semi-hydrous form of calcium sulphate (CaSO4.½H2O), disposed between two facing membranes, typically paper or fiberglass mats.
The most commonly used drywall is one-half-inch thick but can range from one quarter (6.35 mm) to one inch (25 mm) in thickness. For soundproofing or fire resistance, two layers of drywall are sometimes laid at right angles to one another. Drywall provides a thermal resistance, or R value, of 0.32 for three-eighths-inch board, 0.45 for half inch, 0.56 for five-eighths inch, and 0.83 for one-inch board. In addition to increased R-value, thicker drywall has a slightly higher Sound Transmission Class (STC) rating.
Conventional interior walls in homes or buildings have opposing sheets of drywall mounted on a stud frame or stud wall. In this arrangement, with the drywall panels having a ½-inch thickness, the interior wall measures an STC of about 33. Adding fiberglass insulation helps, but only increases the STC to 36-39, depending upon the type and quality of insulation, as well as stud and screw spacing. As wallboard is typically comprised of several sheets or panels, the small cracks or gaps between panels, or any other cracks or gaps in the wall structure are referred to as “flanking paths,” and will allow sound to transmit more freely, thus resulting in a lower overall STC rating.